For some time, it has been known in the art that it is possible to produce a 2-dimensional image that has the appearance of being 3-dimensional when viewed from a single angle, by the use of 4-color printing. The image however, does not change with viewing angle as a true 3-dimensional image would. In recent times, it has been found that realigning magnetic pigment particles by the application during printing of a magnetic field to a wet film of ink containing said particles, can produce an image which changes with viewing angle. This process involves the use of specialized pigments. There are also modifications required to the presses in order to apply the magnetic field to the wet ink film to produce a simulated 3D or etch effect, and if a specific image is required, these modifications can be complicated and expensive.
The following references describe the production of printed images having a 3-D appearance by different means.                US 2006/0150854A1—Sicpa Holdings        US 2009/0200791A1—Sicpa Holdings        US 2007/0172261A1—JDS Uniphase        US 2003/0165637A1 & U.S. Pat. No. 6,759,097 B2—Flex products        U.S. Pat. No. 5,223,360A—Merck        
The references listed above all refer to the production of 3-D images for security or decorative use. They all rely, however, on the use of special magnetic or magnetizable pigments. They also rely on aligning said pigments in a magnetic field, using either permanent or electromagnets. It is the application of the magnetic field which presents the greatest difficulty. If continuous lines are all that is required, it is sufficient to position the magnets somewhere between the printing and drying stages of production. If however, a specific image is required that is specifically placed, the placement and application of the magnets is not so straightforward. The magnets have to be in stationary contact with respect to the print for long enough to develop the image without smearing. Some prior art documents do not address this, others indicate placing the magnets within the impression roller or plate.